Are the founders legally obligated to return the $6MM they took off the table or is it a moral obligation? (Or is there no obligation whatsoever) And if it is

Are the founders legally obligated to return the $6MM they took off the table or is it a moral obligation? (Or is there no obligation whatsoever) And if it is a moral obligation, what would incentivize them to do so - is it to save their reputation in the future?